In the electronic integrated circuit industry, there is a continuing effort to increase device speed and increase device densities. Optical systems are a technology that promise to increase the speed and current density of integrated circuits. Various components of optical and electronic integrated circuits can be discrete elements made from glass or clear plastic or alternatively can be formed from a semiconductor material, such as silicon.
The majority of the semiconductor industry efforts, including a massive number of person-hours of research and development, has focused its efforts on silicon-based electronic circuits in attempting to make electronic circuits faster and more reliable. While other semiconductor technologies such as Ga—As have shown great promise, the emphasis on the research in development in Silicon has reduced the rate of development of the other semiconductors. This concentration on silicon devices has been rewarded by quicker and more reliable silicon devices, however the rate of improvement of silicon-based device speed has decreased in recent years.
While optical integrated circuits show much promise, there are certain inherent benefits to optical circuits. For instance, at a single level, two electrical conductors cannot be made to cross each other. By comparison, one ray of photonic radiation (light) may be made to cross at an angle another ray of photonic radiation without interference there between. Light can travel faster between locations that are separated by a great distance than electricity. Fiber-optic systems have thus been applied to backbone-type applications such as SONET, that relies on a fiber-optic ring technology to provide high bandwidth, high speed data transfer. Providing frequent conversion between electrical and optical signals slows down the data transfer rate and increases the potential of error in interpreting data levels (differentiating between a digital high and a digital low value). For smaller distance optical communication distances, the benefits of optical communications are not quite as evident and the acceptance of optical systems has been less than overwhelming. It is at least years in the future until the optical industry appears able to be realize a commercially viable “last mile” connection between the communication backbone or computer network backbone and the end user that is necessary for optical systems to be fully accepted. Optical computers are even further in the future. One uphill battle of optical systems is that electronic systems have been developed so much earlier and are already implemented in many regions. The development of large-scale optical systems have shown
It would be desirable to provide a variety of silicon-based optical circuits to compensate for variations in the operating parameters such as temperature and device age. In one aspect, it would be very desirable to provide systems that could provide end-user to end-user optical signal transfer for communication systems or computer network systems.